Classic Carburettor Removal etc

[Mick Taylor]

Hi all, I have had my Classic running today after going through the electrics, and given that it was standing for ten years it seems amazingly good. It has a new Electrex R/R and a replacement ballast resistor and it charges perfectly. I found a tiny device that has allowed the charge warning lamp to keep working with the new R/R as it doesn't come with a warning lamp output. Everything else works as it should.The fly in the ointment though seems to be the carbs. The engine starts perfectly from cold on a fast idle and warms up readily, it is very responsive to throttle and seems remarkably smooth, however if I allow the revs to drop below about 1,200rpm it starts chugging, if I then open the throttle it gets very sooty (rich) and will either recover slowly and then rev normally or more likely just die. I feel amazingly lucky that it runs as well as it does.I haven't touched the carbs yet; ordinarily that would be among the first jobs on a bike that has been standing, but I'm awaiting a W/S Manual from ANIL and don't even have an exploded diagram as yet. I was about to remove them until I noticed a small rather vulnerable looking rigid pipe partly hidden behind the inlet tract and without information I was concerned I might damage something.SU carbs are alien to me, though I'm very familiar with the typical 1970s Japanese CV carbs. Is there anything to be particularly wary of in removing the carbs and do they even have a conventional low speed idle circuit? Are there any airways or jets etc that typically get blocked or gummed?All advice gratefully received.........Mick.

[Interpol2471]

I have just written a huge reply on this and the bl##dy website for some reason would not upload and I lost the lot.Someone else can write it up I have lost my teddy now

[Richard Negus]

Prima donna's - give up just cos' they made a mistake. Or an infection from the NOC Forum - tempers are getting quite frayed there about lost posts.Back to the question..remove fuel pipes from carbs.remove battery .undo two M8 cap head screws at the carb inlet casting to frame..wriggle carbs off; they may come with induction pipe and idle pipe still attached as they are a push fit at each end. The idle pipes are the small curly pig's tail pipes and only fit one way/one side. Easier to re-assemble if you keep these attached to the engine..loosen solderless nipple on choke cables and take carbs to workbench.This is complicated on the right side by the 'fast idle rod', a rigid connection between choke and throttle; easy to disconnect the spring clip at the engine end, and an absolute bu&&er to replace. Patience, patience, patience .................... and several spare clips.For the carbs themselves, a good clean, fit viton-tipped float needles, set the jet heights, replace the O-ring on the choke mechanisms! and use SAE40 oil in the dashpots. Nothing else needed.When re-fitting, allow about 3mm of slack in the choke cable and a bead of silicone goo on the carb inlet O-ring.Don't hesitate to ask!R

[Mick Taylor]

Thank you for that Richard, much appreciated.The various O rings are on order so I hope to have it back together by the end of the week if all goes to plan. Setting the float heights took a little working out as it is so unlike the typical Japanese method of simply measuring to the bottom of the float......but I got there in the end.Thanks...........Mick.

[Interpol2471]

Thanks Richard I used the phone worked much better for me Yes I dont know what happened one minute all was fine and then the forum monster struck and crashed my post...